1. Field of the Invention
This invention relates to fishing reels, and more particularly to an improved structure for reciprocating the spools of spinning reels.
2. Description of the Related Art
Japanese Utility Model Unexamined Publication No. Sho. 61-152269 discloses a spinning reel for fishing with a spool having a tapered surface. Specifically, the spool has a so-called "forward tapered surface" in which the diameter of a winding barrel portion of the spool gradually decreases from a rear portion thereof toward a front portion thereof. Such a tapered construction lightens the resistance of the fishing line when it is let out, rendering casting far easier than otherwise. Japanese Utility Model Registered Publication No. 3007531 discloses a different taper design, wherein the diameter of the winding barrel portion gradually decreases from the front portion toward the rear portion. In the case of this design, the so-called "inverse tapered surface" prevents the fishing line from collapsing when the fishing line is let out.
Japanese Utility Model Examined Publication No. Sho. 63-2568 discloses an innovation relating to the cam shaft of a fishing reel. According to the publication, a traverse cam shaft for reciprocating a spool back and forth has a cam groove with a longitudinal pitch that gradually increases from a front portion toward a rear portion. As a result, the line let-out resistance of the fishing line wound around the spool is reduced.
However, even though designing the winding barrel portion to have a forward tapered surface can lighten the line resistance during casting, when the fishing line is cast, the wound line in the vicinity of a spool front flange may collapse forwardly, resulting in a large amount of the wound line being let out at once. This is caused by various factors, including (i) resistance between the line windings during the casting operation, and (ii) variations in the line, such as in the width of the line, the tension in the line, and the like. As a result, the fishing line cannot be let out smoothly after all, which, among other drawbacks, has a negative influence upon the casting distance.
On the other hand, use of the inverse tapered surface design for the winding barrel portion has a stabilizing effect on the wound fishing line and tends to prevent the fishing line from collapsing forwardly during casting. However, the inverse taper causes the line let-out resistance to increase, which, in turn, negatively impacts the casting distance, just as above.
Further, both the forward and the inverse tapered surface designs have a drawback in that special cutting or tooling is necessary to shape the spool to have the forward tapered surface or the inverse tapered surface. This increases the cost of manufacture of the spool, which is itself another problem.
The conventional approach, described above, of changing the pitch of the cam groove of the traverse cam shaft is designed to increase the amount of wound line from the front portion of the spool toward the rear portion thereof, whereby the line let-out resistance is reduced. This approach, however, also gives rise to the line-collapsing phenomenon.